Bearings each composed of a back metal and a bearing layer of resin material adhered to the inside face of the back metal (here inside face means the load supporting side face or inner circumferential face of the bearing) are adopted in machines such as steam turbines, gas turbines, etc. as radial journal bearings and thrust bearings for supporting shafts rotating at high speed.
The bearing layer of resin material is lower in heat conductivity as compared with bearing layer of cupper alloy such as white metal, etc., and heat generation in bearings of rapidly rotating shafts is severe, so temperature rise in such bearings is significant owing to large amount heat generation and low heat conductivity. Therefore, it is required to operate the machines while monitoring bearing temperature.
A bearing composed of a bearing layer of resin material and a back metal to which the bearing layer is adhered and provided with a bearing temperature measuring device is disclosed in document 1(Japanese Laid-Open Patent Application No. 2006-112602).
FIG. 9 is a partial longitudinal cross-section of a radial bearing showing a bearing temperature detection portion disclosed in the document 1.
As shown in FIG. 9, the radial bearing 01 has the bearing layer 02 of resin material adhered to the inside face of the back metal 03. The bearing 01 is provided at the bearing temperature detection portion with a heat insulating member 03g fit into a hole 03f having a bottom bored into the back metal 03, a metal piece 03d for sensing temperature which is fit into a through hole 03c bored into the bearing layer 02 so that its top end face is level with the sliding surface of the bearing layer 02, and a temperature detector 03h which is connected to the temperature measuring metal piece 03d and extends through a through hole 03e bored into the back metal 03 to be connected to a temperature instrument not shown in the drawing.
Temperature of the temperature measuring metal piece 03d is detected by the temperature detector 03h as the temperature of the bearing material 02.
In the bearing shown in FIG. 9, the temperature measuring metal piece 03d is fit into the through hole in the bearing layer of resin material such that the top end face of the temperature measuring metal piece is level with the sliding surface of the bearing layer 02 on which bearing load is supported, and this prior art has a disadvantage as follows.
Young's modulus of the resin material of the bearing layer 02 is smaller than that of cupper alloy such as white metal (Young's modulus of white metal is about 52 GPa, whereas that of resin is about 13 GPa). Therefore, compressive deformation due to bearing load exerting from the rotating shaft is larger in the case of the bearing layer as compared with the case cupper alloy such as white metal is adopted as such bearing layer.
With the prior art as shown in FIG. 9, as the temperature measuring metal piece 03d is tightly fitted with the bearing layer 02 so that its top end face is level with the sliding surface of the bearing layer 02, such a state occurs that the temperature measuring metal piece 03d protrudes from the bearing layer 02 toward the rotation shaft when compressive deformation increase due to increased bearing becomes large, and the rotation shaft is scratched by the protruded metal piece, resulting in decreased load bearing capacity, and also may be resulting in occurrence of damage to the rotation shaft.